Safety electric fuse.



s. w. HUFF.

SAFETY ELECTRIC FUSE. I APPLICATIONTILED APR. 27,1914.

1 ,188,78 6 I Patented J une 27, 1916 2 SHEETS-SHEET I.

y i j 3w S. W. HUFF.

SAFETY ELECTRIC FUSE.

APPLICATION man APR. 27. 1914.

PatentedJune I 27,1916. 2 SHEETS-SHEET 2.

SLAUGHTER W. HUFF, OF BROOKLYN, NEW YORKv SAFETY ELECTRIC FUSE.

Application filed April 27, 1914.

T 0 all whom it may concern Be it known that 1, SLAUGHTER W'. Herr, acitizen of the United States of America, and resident of Brooklyn, inthe county of Kings and State of New York, have invented certain new anduseful Improvements in Safety Electric Fuses, of which the following; isa specification.

This invention relates to fuses to be introduced into an electriccircuit and embodying a conducting body that will fuse and interrupt adangerous current to prevent the latter from. injuring machinery whichis being fed thereby; and particularly to that class of such fuses whichembody a protecting housing or casing to confine the molten metal andgases therefrom and prevent damage at the time the fuse is blown.

More specifically, the present invention relates to that type ofinclosed fuses which employ knife blade terminals extending within thecasing to receive the fusible link or conductor, and extending beyondthe casing for connection with any form of support usually found uponthe switch. board; and the invention has for its object to provide forthe assembly of the knife blade terminals with the fuse casing, in amanner that will not only provide .an improved construction, but whichwill be very much more economical in material consumed in manufactureand time required for prepa ration of the parts and for assembling.

In carrying out the invention, the knife blades have formed upon them,or are otherwise provided withlspurs or projections which are caused toembed themselves in the inner walls of the casing. Prefe'ably, the

introduction of the knife blades takes place 7 after they are assembledwith the fusible link, so that the conducting parts can thus beassembled to the best advantage, and they are brought to position byintroducing the assembled conducting parts .endwise through the casing;but the invention is not limited to this particular method ofprocedure.v

Preferably also, the l'readth of the knife blades correspondssubstantially with the diameter of the casing and the casing is firstdistorted to enlarge its diameter in one direction and while the knifeblades are being inse ted, and sufficiently to freely admit the knifeblades with their spurs, after which the casing is restored toapproximately its original form in a manner to cause the spursSpecification of Letters Patent.

Patented June 27, 1916..

Serial No. 834,754.

to embed themselves into the material of the casing. But the inventionis not ii ited to this precise procedure, for I desire it to beunderstood that the breadth of the knife blades may be greater than theoriginal diameter of the casing. so that thelatter will not be whollyrestored from its first distortion, but may be caused to envelop thelock ing spurs with but a partial return movement. Or the originaldiameter of the casing may be sufiicient without distortion to admit theknife blades with the spurs, and the embedding of the spurs in thematerial of the casino; may be developed by permanently reducing thedian'leter of the casing and retaining it in such distorted form, theessential feature being the interlock of the blade with the tubularcasing by embedding the connecting spur, as distinguished fromintroducing a stud through the casing wall into the blade, orintroducing into a pre viously prepared opening in the wall, aprojection integral with or otherwise carried on the blade; and theadvantages, aside from economy of broduction, being accuracy of positionof the blades relatively to the fusible link, rigidity of grip upon theblades, and unimpairment of the hermetic walls. In every instance,suitable end caps are preferably applied over the ends of the casing toretain the form of the casing and its assembled 'relation with the knifeblades.

The invention will be fully understood upon reference to theaccon'ipanyingf drawings, in which Figure 1 is a transverse section, andFigs. 2 and 3 two longitudinal sections in planes at right angles toeach other, of a fuseembodying the present invention; Figs. 4. and 5 areviews suggesting the apyflication of pressure for the purpose ofeffecting a first distortion sufficient to admit the knife blades,

and a second or restoring distortion to em-.

bed the spurs and interlock the knife blades with the casing; Figs. 6, 7and 8 are detail views suggesting the application of dies for thepurpose of swaging or upsetting the edges of the knife blades to formthe locking projections or spurs; Fig. 9 is a detail view suggesting anmltiplicity of interlocking spurs that may be provided, instead of asingle spur on each side of a blade.

1 represents a casing which is commonly made of fiber tubing, and 2represents caps such as are usually employed in the type of fuse towhich the invention relates. 3 are the knife blades which pass throughslots in the caps 2 and are connected at their inner ends with fusiblemetal 4, either in the form of a plurality of wires, or in some otherform that may be desired.

It is customary to fill the casing of a fuse of this type with someinert matter that will largely fill'the air space and completely embedthe parts within the casing; hence,

there are several steps in the manufacture to be carried out after theknifedolades are in troduced and before the fuse casing is finallyclosedl For this reason, it is desirable to have some means for holdingthe knife blades in place independently of the caps to avoid injury tothe delicate fuse metal, which connects the knife blades, instead ofleaving the knife blades free, as in cases where the cap and the knifeblades are secured in position by the same screws passing through thecapand intermediate wall and into the knife blades. On the other hand, itis a source of additional expense for material to use separate screws orany screws at all for holding the knife blades in the casing, and anexpense in time to have to drill and thread holes in the knife bladesand then locate them relatively to the holes in the ca sing and insertthe small screws that must be employed, or to employ other forms ofstuds or projections that require registering with 'prepared openings inthe casing. For these reasons, the present invention employs projections5 on the knife blades 3, which au tomatically embed themselves and,therefore, automatically locate the points at which they enter intoengagement with the inner walls of the casing 1. This interengagement isaccomplished by constructing the projections in the form of spurs whichare adapted to embed themselves into the material of the casing when thewalls are pressed firmly against the spurs. This is convenientlyaccomplished in different ways. One method is suggested in Figs. 4 and5, according to which the breadth of the knife blades is approximatelythe same as the normal diameter of the casing, but is pressed between apair of dies 6 until its diameter is elongated sufficiently to receivethe knife blade with its spurs, after which the pressure may be relieved in that direction, and then applied in a direction perpendicularthereto to press the walls firmly upon the spurs, by dies 6 as suggestedin Fig. 5. A second pressing step may, of course, be omitted if desiredand the inherent resiliency of the casing be Ooplos of this potsnt no Inobtslned (or casing is being shifted from the relied upon to develosufficient embedding or biting into the Wal s to prevent displacement ofthe knife blades. This gripping effect, by the resiliency of the casing,will assist in holding the knife blades while the position of Fig. 4 tothe position of Fig. 5. 5

After the .knife blades are assembled with the casing and the necessaryfiller has been introduced, the caps 2 are put in place and secured inany suitable manner, as for instance by screws entering holes that maybe drilled after assembly, or by cementing, or by merely forcing atightly fitting cap over the end of the tube, and when so applied thecaps cooperate with the embedded spurs or interlocked projections todevelop transverse rigidity in the knife blades.

As suggested in Fig. 9', any desired nun ber of spurs may be formed onthe knife blades.

The knife blades with any desired form of projection thereon may becast, stamped, or otherwise formed, but I prefer to use standard stockof strip brass or copper cut to lengths and to form the spurs thereon byswaging or upsettingbetween dies 7, as suggested in Figs. 6, 7 and 8.

As already suggested, the invention may be measurably realized byinterlocking the knife blade with the casing through means of a bayonetjoint groove 8 (Fig. 10) receiving the lug or projection 5.

I claim 1. In a safety electric fuse, av tubular casing, a knife bladeterminal piece having a breadth corresponding substantially to adiameter of the tubular casing, and self embedding spurs carried by theterminal pieceand embedded in but not penetrating through the walls ofthe casing.

2. In a safety electric fuse, a tubular easing, a .knife blade terminalpiece having a breadth corresponding substantially to a diameter of thetubular casing, and self-embedding spurs carried-by the. terminal pieceand penetrated into but riot through the walls of the casing, and a bandor hoop snrrounding the casing and overlying the portions of the wallswhich the spurs penetrate.

The foregoing specification signed at Brooklyn, New York, this 6th dayof April,

SLAUGHTER W. HUFF. In presence of L. E. COLWELL,

JOHN A. THAKE.

flvo cents each, by dressing the "Commission: of hunts. Washington, I).0."

